Foldable mobile phones having an upper case and a lower case connected by a hinge member that connects and able to be opened and closed are widely used in recent years. These foldable mobile phones have started having additional functions of GPS (Global Positioning System) receiving functions. GPS utilizes circularly polarized waves, instead of linearly polarized waves used in mobile phone communication. Accordingly, to have GPS receiving functions and achieve high reception performance, circularly polarized wave antennas for GPS reception need to be mounted in the case of the foldable mobile phone.
Circularly polarized wave antennas for mobile phones are disclosed in, for example, Patent Document 1 and Patent Document 2. The circularly polarized wave antennas disclosed in Patent Document 1 and Patent Document 2 capture circularly polarized waves with cross-bar elements provided in the flip-down covers of the mobile phone. In addition, these circularly polarized wave antennas capture polarized waves appropriately in the state (hereinafter referred to as “calling state”) where the user makes a call holding the mobile phone in his hand.
Circularly polarized wave antennas for mobile phones also include the one disclosed in Patent Document 3. The circularly polarized wave antenna disclosed in Patent Document 3 performs polarization diversity operation by switching two cross elements provided inside the mobile phone and supplying power at a phase difference of 90 degrees.
Patent Document 1: Japanese Patent Application Laid-Open No. 2000-183635
Patent Document 2: Japanese Patent Application Laid-Open No. 2000-353911
Patent Document 3: Japanese Patent Application Laid-Open No. 2002-16433